Time to disease progression or death in a) the whole Bosentan Use in Interstitial Lung Disease (BUILD)-1 study population and b) the subpopulation with biopsy-proven idiopathic pulmonary fibrosis. ·········: treatment with bosentan, ––––: placebo. a) Hazard... Time to disease progression or death in a) the whole Bosentan Use in Interstitial Lung Disease (BUILD)-1 study population and b) the subpopulation with biopsy-proven idiopathic pulmonary fibrosis. ·········: treatment with bosentan, ––––: placebo. a) Hazard ratio (95% confidence interval): 0.613 (0.328–1.144); p = 0.119. b) Hazard ratio (95% confidence interval): 0.315 (0.126–0.789); p = 0.009. K. K. Brown, and A. U. Wells Eur Respir Rev 2008;17:116-122 ©2008 by European Respiratory Society